The paper deals with the characterization of lower (p, q)-type with respect to a proximate order of an entire function in terms of coefficients and exponents of its power series expansion. In particular, the problem proposed by Bajpai et al. [Trans. Amer. Math. Sac. (1975)], and subsequently, left open by Juneja et al. also [J. Reine Angew. Math. (1977)] has been solved.